Awesome! Thanks for sharing this. I just got one of the Frostwave Resonator (MS-20 filter clones) and was looking to figure out some way to get a control signal out of the G2 in order to control the Resonator...I've become fond of using the Resonator as the main filter of a G2 patch, running the audio out to the filter and then back into the nord, but I can't live without some kind of filter envelope applied to my sounds.

I had been debating a MIDI-CV converter, but was unsure of possible latency problems. Mosc have you even noticed anything along these lines with MIDI-CV converters that you have used? Would they easily be suitable for tight filter envelope control and such?

Thanks.

It was a pleasure to share this "exotic solution"!

I'd be interested in hearing your G2+Resonator combo - do you have any sound clips that you could post?

BTW, what control voltage range does the Resonator use for filter cutoff?_________________varice

I'd be interested in hearing your G2+Resonator combo - do you have any sound clips that you could post?

I didn't record any clips yet, I plan to this weekend. I will post them here when I do.

The MS-20 filter (Resonator) has such a great sound, even just driving the input of the unit with the filter's wide open sounds great. Using the HP filter and LP together is great at fine tuning the sound; easy to cut out some of the ultra low woofy sounds that can get out of control with a resonant LP filter. Oh yeah, and both will self oscillate...I had a lot of fun just tweaking the cutoffs of both filters while they were in this state .

It's a very different sound than the Moog filter, which in my opinion is much clearer/cleaner than the MS-20. But, this is one of the reasons (or I guess maybe the only reason) that I like the MS-20 filter; because it has that "dirty" character.

varice wrote:

BTW, what control voltage range does the Resonator use for filter cutoff?

The Korg stuff of that era (MS-10, MS-20, etc) used a Hz/V scale and since the Resonator is supposed to be an exact replica, it too uses this scale. Off the top of my head I believe the range is -/+12V but that seems kinda high...I'll have to read the manual when I get home._________________...if the computer will not startup, something else is wrong with the computer...

Did you happen to try processing your G2X sound with your Moog filter?

Yes, the Moog filter sounds different from the G2 Classic or Nord filter modules. I have spent a lot of time listening to them and comparing them. They are different, but I can't say which is better. The G2 filters are polyphonic - a big advantage. _________________--Howard
my music and other stuff

BTW, what control voltage range does the Resonator use for filter cutoff?

The Korg stuff of that era (MS-10, MS-20, etc) used a Hz/V scale and since the Resonator is supposed to be an exact replica, it too uses this scale. Off the top of my head I believe the range is -/+12V but that seems kinda high...I'll have to read the manual when I get home.

I had a peak at the Resonator manual last night and it didn't actually mention the use of the Hz/V scale (so until I get a CV source to test, I'll keep assuming that it does use it). It did, however, say that any signal in the 0-10V range would be acceptable._________________...if the computer will not startup, something else is wrong with the computer...

Polyphonic... and extremely low temperature drift... virtually perfect pitch tracking... absolutely repeatable parameter settings... and parameter setting recall from memory... and digital readout displays of the settings of the cutoff and resonance knobs... and controls that won't wear out or get noisy... and a faceplate that can magically be renamed and set to different colors..._________________varice

BTW, what control voltage range does the Resonator use for filter cutoff?

The Korg stuff of that era (MS-10, MS-20, etc) used a Hz/V scale and since the Resonator is supposed to be an exact replica, it too uses this scale. Off the top of my head I believe the range is -/+12V but that seems kinda high...I'll have to read the manual when I get home.

I had a peak at the Resonator manual last night and it didn't actually mention the use of the Hz/V scale (so until I get a CV source to test, I'll keep assuming that it does use it). It did, however, say that any signal in the 0-10V range would be acceptable.

Oh yes. the Korg Hz/V thing. Did the manual mention using expression pedals? Those (I think) are just linear pots - would probably produce a signal more in line with a V/Oct control._________________varice

Oh yes. the Korg Hz/V thing. Did the manual mention using expression pedals? Those (I think) are just linear pots - would probably produce a signal more in line with a V/Oct control.

Yes actually it did. It mentioned that you could combine a 9V battery with a standard expression pedal to act as a CV controller for the unit. Although it didn't specifically say, I'm guessing the Resonator does not provide power out to the pedal (a al Moogerfoogers) which is why the 9V batter is required._________________...if the computer will not startup, something else is wrong with the computer...

I changed the connection point for the DC CV output from C103 to C101 at pin 1 of the LM833 opamp. A 1K resistor was added for current limit protection. This point has a better output signal._________________varice

While tuning the MF-101 to track keyboard note values, I noticed that there was a short period of time, maybe 200 - 300ms, just after a CV change that the CV signal seemed to lag just before settling to the final value. I patched an LFO square wave to the output and used my o'scope to confirm this. The signal would instantly change to about say 97% of the final value, and then take a few hundred ms to settle to 100%. I do not know why. I decided to try to find a point in the circuit with a better signal performance for Output 4 and found it where C101 connects to the pin 1 output of an LM833 opamp.

I sure wish I had schematics of the G2 circuits, but I doubt seriously that Clavia would give them to me._________________varice

...another way around this (and another excuse to aquire more gear) is something like the peavy spectrum analog filter (yes, i know it's peavy, but it rules). it has full midi implementation, and it's own envelope generators...basically a standard analog synth with midi for all knobs and 3 inputs instead of oscillators.
deknow

...another way around this (and another excuse to aquire more gear) is something like the peavy spectrum analog filter (yes, i know it's peavy, but it rules). it has full midi implementation, and it's own envelope generators...basically a standard analog synth with midi for all knobs and 3 inputs instead of oscillators.
deknow

Interesting...

How does the Peavey Spectrum Filter sound compare to a Moog classic ladder filter? I do not know how the Peavey Filter sounds. The Peavey manual describes the filter as an "American classic" (Hmmm... as opposed to a modern un-American? ) design. If, in any case, the Peavy Filter has a good unique sound character, I would add it to my list of future gear considerations.

Using the Peavey Filter instead of my Frankenstein G2X/MF-101 modification, you would gain MIDI control and memory preset of the filter resonance, but you would not have the ability to use any of the precise G2 control signals to modulate the Peavey Filter cutoff freq.

On the other hand, if you can afford it, instead of the Peavey Filter, you could get a Moog Little Phatty or even a Moog Voyager and interface these the same way with the a G2 _________________varice

i have the peavey, but haven't used it in quite a while (although this thread is making me think about dragging it out).

it is a moog style filter, so it should at least sound in the same "familly" as the moogerfooger. looking at a few reviews on sonic state, some people complain about zipper noise when moving knobs too quickly....i don't remember this being a problem, but i used this mostly at a time when i wasn't so focused on such things....and it's not uncommon to see reviews on harmony central that make false claims about gear not working right.

in use with the g2, my guess would be that it's better to use the g2 to control the parameters of the built in envelopes of the peavey than it is to fire envelopes off in the g2 and send cc for cuttoff and/or amplitude. it could sit on the same channel as the synth being processesed, or you could run it on it's own.

i hope this is helpful...imho, this is one of the most underapreciated pieces of gear out there.

I took another look at the Peavey Spectrum Filter. The manual indicates that sysex commands can be used to edit the parameter settings, but there seems to be only one MIDI CC that can be used - and it is fixed to only affect the filter cutoff level. Is it possible to assign MIDI CCs to the other parameters?_________________varice

...i just went to look it up, and am embarased to admit that you are correct!

...my only excuxe is that it has so many nice knobs, i've never needed to send it cc data (but it would be durned important if you are going to slave it to a g2). so you can controll fiter cutoff, and you have 99 patches, but only sysex for the rest of the knobs

i hope you didn't go out and buy one expecting it would respond to cc's!

...i just went to look it up, and am embarased to admit that you are correct!

...my only excuxe is that it has so many nice knobs, i've never needed to send it cc data (but it would be durned important if you are going to slave it to a g2). so you can controll fiter cutoff, and you have 99 patches, but only sysex for the rest of the knobs

i hope you didn't go out and buy one expecting it would respond to cc's!

Oh no - I haven't bought one. I downloaded the manual back when you first mentioned the Spectrum Filter. On the first read I didn't even catch that not all of the controls could be assigned to MIDI CCs - I just assumed that they could be assigned. I recently got more serious about checking out the filter and read the manual again a bit closer. It really is too bad that Peavey didn't make the filter more MIDI friendly!_________________varice

i got an roland monophon expander... like a 101 without keys or sequencer... could be a ggod extension to the G2...especially because i want to use it for sub bass mainly...there 100% exact tuning is usually rather ugly than beneficial..
I thinkl it would work to scale the output well enough to achive a working octave or 2... in the end a bassline usually dont has 10 different notes

i got an roland monophon expander... like a 101 without keys or sequencer... could be a ggod extension to the G2...especially because i want to use it for sub bass mainly...there 100% exact tuning is usually rather ugly than beneficial..
I thinkl it would work to scale the output well enough to achive a working octave or 2... in the end a bassline usually dont has 10 different notes

For sub bass pitch control this mod should work. If the Roland can work with about 0 to +4 volts, you should be good to go._________________varice

only thing that scares me is the szenario where you run in stupid stage situations where you get hot stageboxes...

You mean mains voltages ?

The only extra risk of making the outputs DC would be with high external DC voltages, although with AC coupling they would also give a spike that could destroy a lot. For AC (i.e. mains voltage) making the outputs DC would not change much.

Still you could add some protection for the outputs of course, some diodes and a few resistors would do the job without really altering the sound (the levels would drop a tiny bit further) - but it would require some more soldering to be done on the G2's internals._________________Jan
(yawning shifts perceived pitch, making things more interesting)

I'll assume a maximum external voltage of 50 V, being the amount of phantom voltage you'd want to protect against (it will have some margin). And I'll assume a device supply voltage of 5 V.

D1 and D2 are general purpose silicon diodes.

The diodes are said to conduct when a forward voltage is applied greater than about 0.6 .. 0.7 Volt over them. In that case a large current can flow through them. In the given configuration D1 would conduct for voltages greater than the supply voltage + 0.6 V. D2 would conduct for voltages smaller than - 0.6 V. This is the protective function.

Diodes conduct a little bit as well for reverse voltages, this current however is so small (typically less than 1 u(micro)A that it will not perceptebly influence the sound.

R1 is chosen such that for an external voltage of 50 Volts about 10 mA will flow intgo the power supply of the device. The assumption implicitly made here is that the device output will withstand short circuits against both ground and positive supply voltage - a reasonable assumption for modern outputs (IMHO). And it is assumed that 10 mA current injection into the power supply will not harm the device, areasonable assumption for a G2 I think.

This results in R1 being 50 - 5 V / 10 mA = 5 kOhm.

A typical bad case input impedance of the device connected to the protected output might be 50 kOhm. This would result in a signal loss of about 10% - or -0.1 dB (2 dB difference is about the per_________________Jan
(yawning shifts perceived pitch, making things more interesting)

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